96 DEPOSITS OF PHOSPHATE OF LIME. [bull. 46. 
acidulated state. Besides this, they contain considerable phosphate of 
iron, which causes a superphosphate, made from such nodules, to have 
a sticky consistency and to be very liable to u revert" to an insoluble 
condition. 
The Crag nodules resemble those of the Cretaceous formation, as well 
as some of those of South Carolina, in the fact that the exterior part 
often contains more phosphoric acid than the interior. The following 
analyses by T. J. Herapath 1 illustrate this fact : 
Exterior. Interior. 
( 1.105 per ceDt. fluoride of lime. 0.611 per cent, fluoride of lime. 
I 40.019 per cent, phosphoric acid. 34.015 per cent, phosphoric acid. 
3.996 per cent, fluoride of lime. 1. 961 per cent, fluoride of lime. 
32.043 per cent, phosphoric acid. 21. 046 per cent, phosphoric acid. 
History of the rock phosphates of England. — The Greensand of England 
has been used as a fertilizer for many generations. As early as 1790 it 
was considered so valuable as a soil stimulant that it was carried in 
carts, sometimes for m any miles, all over the counties of Essex and 
Kent. Immense pits, dug in the Greensand marl, concerning which 
there is no historic record and which are now overgrown by large oaks 
and other forest trees, bear witness to the great value placed on this 
marl in by-gone times. A remarkable example is seen at Worldham, 
where there is a large excavation 15 feet deep, from which, once, 
thousands of tons of greensand were removed. But the heaps of phos- 
phatic nodules which are often found near these pits, and which seem 
to have been thrown away as worthless, show that the value of this 
part of the bed was not known. 
It was not until nearly the middle of this century that the agricultural 
value of these nodules was appreciated. Doctors Mantel, Buckland, 
and Fitton, in the early part of the century, pointed out the existence of 
beds of nodules and fossils in the Cretaceous and Tertiary formations 
of England, but simply spoke of them as remarkable beds of fossils and 
nodules. Mr. Berthier, in 1820, also made analyses of similar nodules 
found in France. But their use as a plant food was not recognized 
until Professor Henslow made a study of the Eed Crag nodules at Fe- 
lixtow in 1842, and suggested their use in agriculture before the Brit- 
ish Association in 1845. It was at this time that the name coprolite, or 
fossil dung, was first given to these nodules by Professor Henslow. 
At a later date he saw his mistake in believing the phosphatic masses 
to be of coprolitic origin, and considerably modified his views. It was 
certainly a most unfortunate name, as it has since been shown that real 
fossil dung is a thing of very rare occurrence, and hence the name cop- 
rolite, as applied to beds of nodular phosphates, is misleading. 
4-mong the most active of the early advocates of English phosphates 
] Jour. Royal Agric. Soc 3 1851. 
